When do you delete a site that's 404

[bluebrit]

There are link checkers you could use but its better to do it manually IMO. That way if you click a link and its not what you expected or it's redirecting for example your able to deal with it straight away. I usually choose a random page and go through every link on that page. Anything unusual gets more attention and I will send emails if a site is down but if it's a blatant redirect or something nasty, not only do i pull that link but any other the person has submitted.